Technical Is it OK to adapt air cleaner with smaller neck size to a carb with a larger neck size?

Hi guys -

Thinking of using an air cleaner similar to the one in the picture. Problem is that the opening in the bottom of the air cleaner is 4-1/4" while I am fitting it to an Edelbrock 4-barrel with a 5-1/8" neck size. While I am sure it is possible to make an adaptor that makes this fit, the question is would that be a good idea? Or would it restrict the carb? Would it be better to open up the bottom of the air cleaner to match the carb by welding a new base to it?

Appreciate your thoughts.


Bantam

 

I don't see it being any problem,actually that's a pretty cool scoop. HRP

 

For normal applications you will be fine. If you are racing at Indy, then I would worry. I like the new item. I would like to have one.

 

In that situation, the best solution would be to replace the modern Edelbrock carb, with an old Carter AFB which has the smaller neck These were used from the late 50s to the early 70s, mostly on Chrysler products, but also on some GMs

 

So you want to close the effective throat size of the carb by how much?


(Pie r squared)
5.125 = 82.50 sq inches
4.250 = 56.75 sq "

About 32% reduction and creating some sort of velocity killing expansion space right above the throat of the carb.

Easy enough to try it I guess

 

Just take it off when you are drag racing at maximum RPM when you "might" be able to notice a reduction of power as you are going through the lights. If it's for the street, you will never notice a thing. They are Nicson flame arrestors for power boats not the best for dusty conditions but it will keep the June bugs out.

 

A bigger problem is the horrible restriction caused by the tight right angle bends (tight turn) of the "bonnet" portion. Most aftermarket "high flow" air intake systems are made like that too. These hole in the wall aftermarket companies have no CFD (computational fluid dynamics) design or modeling capabilities.

Their design capabilities are limited to "making it look nice".

 

....which is probably why he wants to use this air cleaner, in the first place

 

If it were mine I couldn't live feeding a carb with an air cleaner outlet size smaller that the inlet of the carb.

Frank

 

Try wrapping your hands around your neck and squeezing to reduce your windpipe size 33% and try and breath. See what your engine will be doing trying to breath with that restriction.

 

Nobody has mentioned that the aggregate cross-sectional area of the four barrels of a 4-bbl carb is much smaller than that of the air cleaner throat. As an illustration, four equal-sized round barrels that fill the throat and have no wall thickness between them have a total of 68.629% of the cross-sectional area of the throat. On an actual carb that can be built and made to work in the real world it's probably more like 55-60%.

So, based on 31Vicky's figures there are therefore probably around 45-50 square inches of cross-sectional area, i.e. slightly less than the throat on the air cleaner. Of course the air cleaner will shroud 7/16" of each barrel unless the adapter has enough height to smooth out the transition.

 

Look at a factory air cleaner some of the snorkels are not very big.